Pharmacotherapy and growth factors in the treatment of short bowel syndrome

Gene expression in the adapting small bowel after massive small bowel resection

BACKGROUND

Intestinal adaptation occurs in the residual bowel following the loss or resection of a proportion of the small bowel. The purpose of the adaptive response is to return absorptive and digestive properties to near normal levels. This study employed a rat model of massive small bowel resection (MSBR) to study the adaptive response in the residual terminal ileum and the jejunum. The time points were chosen to reflect changes in gene expression early on in the response, because these are the genes that alter to initiate and maximize the response observed during adaptation.

METHODS

Sprague Dawley rats underwent an 80% resection. Differential display polymerase chain reaction (DD-PCR) analysis was performed on mRNA extracted from the remnant ileum and jejunum 0, 1, 2, 4, and 7 days post-MSBR.

RESULTS

DD-PCR identified 11 genes that were possibly regulated following MSBR. Genes confirmed to be regulated were 16S ribosomal RNA, lymphocyte antigen 6 (LY6)-like molecule, Krüppel-like factor-3 (KLF-3), G-protein-binding protein (CRFG), system A transporter 2 (SAT2), and an intestine-specific gene (similar to mKIAA0493).

CONCLUSIONS

DD-PCR analysis showed regulation of a number of genes not previously known to be involved in adaptation after MSBR or previously characterized in the intestine. These genes may be important in bringing about the complement of changes seen during the adaptive response.

A genetic mechanism for cecal atresia: the role of the Fgf10 signaling pathway

BACKGROUND

Intestinal atresia represents a significant surgically correctable cause of intestinal obstruction in neonates. Intestinal development proceeds as a tube-like structure with differentiation along its axis. As the intestine differentiates, the cecum develops at the transition from small to large intestine. Fgf10 is known to serve a key role in budding morphogenesis; however, little is known about its role in the development of this transitional structure. Here we evaluate the effect of Fgf10/Fgfr2b invalidation on the developing cecum.

MATERIALS AND METHODS

Wild-type C57Bl/6, Fgf10(-/-), and Fgfr2b(-/-) embryos harvested from timed pregnant mothers were analyzed for cecal phenotype, Fgf10 expression, and differentiation of smooth muscle actin.

RESULTS

Wt cecal development is first evident at E11.5. FGF10 is discreetly expressed in the area of the developing cecum at early stages of development. One hundred percent of Fgf10(-/-) and Fgfr2b(-/-) mutant embryos demonstrate cecal atresia with absence of epithelial and muscular layers. The development of neighboring anatomical structures such as the ileocecal valve is not affected by Fgf10/Fgfr2b invalidation.

CONCLUSIONS

FGF10 expression is localized to the cecum early in the normal development of the cecum. Fgf10(-/-) and Fgfr2b(-/-) mutant embryos demonstrate cecal atresia with complete penetrance. Epithelial and muscular layers of the cecum are not present in the atretic cecum. The Fgf10(-/-) and Fgfr2b(-/-) mutants represent a genetically reproducible animal model of autosomal recessive intestinal atresia.

Gastrointestinal hormone secretion after surgery in neonates with congenital intestinal anomalies during starvation and introduction of enteral nutrition

BACKGROUND/PURPOSE

Gastrointestinal hormones modulate gut function in response to enteral nutrition. Infants with a congenital intestinal anomaly with loss of bowel length either pre-or postnatal, who are on total parenteral nutrition for prolonged periods after surgery, are especially prone to a disturbed secretion of gut hormones. The aim of this study was to determine whether circulating gut hormones were altered in these patients and to collect baseline data for future studies in short bowel patients using different enteral substrates.

METHODS

Gastrin, cholecystokinin, and peptide YY were measured in 14 operated neonates who had a congenital intestinal anomaly during starvation and introduction of enteral nutrition. None of the neonates had a short bowel. Fourteen neonates who underwent surgery for other major congenital anomalies served as age-matched controls. Gut hormones were measured with radioimmunoassays.

RESULTS

Postprandial gut hormone values were higher than basal gut hormone values within both groups. Compared with the controls, postprandial gastrin and cholecystokinin were significantly higher in the patients.

CONCLUSIONS

Neonates with a congenital intestinal anomaly in the absence of a short bowel have a similar secretion pattern of gastrointestinal hormones as neonates with a structurally normal intestinal tract, both during starvation and enteral nutrition.